AC not cooling but fan is running
When the fan blows but the air is warm, settings, filters, and outdoor unit airflow are the homeowner checks. Refrigerant leaks and compressor faults need a technician with EPA certification. This page links to the broader outage guide instead of repeating it.
Safety first: when to call a pro
Leave if you smell gas or a carbon monoxide alarm sounds; call 911 or the gas utility from outside. Do not open refrigerant lines, gas valves, or electrical panels. You may slide out a filter or reset a dry breaker once. If the breaker trips again or you smell burning, stop and call a technician.
Filter swaps and thermostat batteries are homeowner maintenance when the equipment is off and dry. Adding refrigerant, wiring repairs, and combustion checks are not. EPA Section 608 covers technicians who service refrigerant circuits.
Are thermostat mode and setpoint correct?
Set mode to cool and the setpoint below room temperature. Replace thermostat batteries if the display flickers. Wait five minutes after changes; some systems delay the compressor. If the fan runs constantly on ON instead of AUTO, you may feel room-temperature air between cooling cycles.
Write the current room temperature and setpoint when you call. That saves repeating the same questions on a service visit.
Is the filter clean and the outdoor unit clear?
Slide the filter out if you can without tools; replace it when light no longer passes through. Outside, keep plants and debris away from the condenser so air can move. Do not bend fins with a hose nozzle. Energy Saver lists filter care and outdoor clearance as routine maintenance, not refrigerant work.
A frozen indoor coil can feel like weak cooling; turn the system off and let ice melt if you see frost on the line set entering the cabinet. Do not chip ice off coils.
When is it time to stop DIY checks?
If the filter is clean, the outdoor unit runs, and air stays warm, the fault may be refrigerant charge or a failed compressor. EPA Section 608 requires certification for work that could release refrigerant. Do not add refrigerant from a retail can. Use the heating and cooling outage guide for gas smell, CO alarms, or total system silence.
See what to do when heating or cooling stops for gas, carbon monoxide, and whole-system outages rather than duplicating those steps here.
Steps
- Set cool mode and a lower setpoint. Fresh batteries if the display is dim.
- Replace a dirty filter. Check ENERGY STAR monthly filter guidance.
- Clear debris around the outdoor unit. Stay away from the fan grille while it spins.
- Shut off if you see ice or burning smell. Ice melt needs the system off.
- Call a technician for refrigerant or compressor faults. Ask about EPA Section 608 certification.
Questions
Can I top off refrigerant myself?
No. Refrigerant handling requires certified technicians.
Is warm air always low refrigerant?
No. Settings, filters, and frozen coils mimic the same symptom.